The present invention relates to agricultural implements and, more particularly, to folding frame arrangements for such implements.
Agricultural implements such as seeders and tillage tools, for example, often have relatively wide frames that must be narrowed for road transport or other purposes. In many instances such narrowing of the frame is effected by folding one or more frame sections vertically or horizontally relative to one another.
It is known in the art to have a pair of relatively foldable frame sections, such as a tool bar or an open box frame, wherein the two sections can be locked rigidly in their unfolded relationship so that one of the sections is effectively an extension of the other. However, in such prior arrangements, a lock or latch that is separate and apart from the hydraulic cylinder mechanism that accomplishes the folding and unfolding action is required in order to lock the sections in their unfolded relationship. In some instances, for example, the operator must leave the cab of the towing vehicle and manually lock and unlock the mechanism. In some other arrangements, extra remotely actuatable hydraulic cylinders and the like are available to accomplish this task.
In the present invention two relatively foldable frame sections can be locked in their unfolded relationship using the same mechanism that accomplishes folding and unfolding of the sections. Thus, there is no need for separate and additional mechanism or devices to accomplish the locking function. Moreover, locking and unlocking can be carried out from the tractor seat as an inherent part of the folding and unfolding operation.
In the present invention one frame section is swingable relative to another during folding and unfolding operations. When the swingable section is down in its unfolded position, it abuts a limit stop on the other frame section. This can be at any selected angular relationship between the frame sections, but in a preferred embodiment the two sections are in end-to-end alignment with one another in the unfolded position. An operating link connected between the swingable section and a hydraulic cylinder on the other section transfers power from the cylinder to the swingable section to carry out folding and unfolding, and a guide on the stationary section controls the link in such a manner that as the cylinder extends and retracts, the swingable section is moved between its and folded and unfolded positions. The geometrical relationship between the various components of the mechanism is such that when the swingable section is in its unfolded position against the limit stop, the operating link is in a locking position with its line of action directed toward a guide surface of the guide, preferably in the neighborhood of being at right angles with the guide surface, so that movement of the swingable section out of its unfolded position is resisted by the guide surface. The hydraulic cylinder that normally pushes and pulls on the link to swing the swingable section is used at this time to retain the operating link in this locking position, only a small amount of force being required by the cylinder to carry out its retaining function since most of the compressive loading from the control link is directed against the guide surface at this time.
Preferably, the guide surface comprises one edge of an elongated guide slot in which guide rollers attached to the proximal end of the operating link are captured for moving back and forth along the slot during folding and unfolding of the swingable section. Thus, a simple, yet effective means if provided for locking the swingable frame section in its unfolded position without the need for additional mechanisms or assemblies above and beyond that which is used to carry out folding and unfolding of the section.